release/src/router/libncurses/doc/html/man/default_colors.3x.html

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  29   * Author: Thomas E. Dickey 1997,1999,2000,2005
  30   * @Id: default_colors.3x,v 1.23 2011/01/03 21:52:27 Tim.van.der.Molen Exp @
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  42 <H1 class="no-header">default_colors 3x</H1>
  43 <PRE>
  44 <STRONG><A HREF="default_colors.3x.html">default_colors(3x)</A></STRONG>                                   <STRONG><A HREF="default_colors.3x.html">default_colors(3x)</A></STRONG>
  45
  46
  47
  48
  49 </PRE>
  50 <H2><a name="h2-NAME">NAME</a></H2><PRE>
  51        <STRONG>use_default_colors</STRONG>, <STRONG>assume_default_colors</STRONG> - use terminal's
  52        default colors
  53
  54
  55 </PRE>
  56 <H2><a name="h2-SYNOPSIS">SYNOPSIS</a></H2><PRE>
  57        <STRONG>#include</STRONG> <STRONG>&lt;curses.h&gt;</STRONG>
  58
  59        <STRONG>int</STRONG> <STRONG>use_default_colors(void);</STRONG>
  60        <STRONG>int</STRONG> <STRONG>assume_default_colors(int</STRONG> <STRONG>fg,</STRONG> <STRONG>int</STRONG> <STRONG>bg);</STRONG>
  61
  62
  63 </PRE>
  64 <H2><a name="h2-DESCRIPTION">DESCRIPTION</a></H2><PRE>
  65        The <EM>use</EM><STRONG>_</STRONG><EM>default</EM><STRONG>_</STRONG><EM>colors()</EM> and <EM>assume</EM><STRONG>_</STRONG><EM>default</EM><STRONG>_</STRONG><EM>colors()</EM> func-
  66        tions are extensions to the curses library.  They are used
  67        with terminals that support ISO 6429 color, or equivalent.
  68        These terminals allow the application to reset color to an
  69        unspecified default value (e.g., with SGR 39 or SGR 49).
  70
  71        Applications that paint  a  colored  background  over  the
  72        whole  screen  do not take advantage of SGR 39 and SGR 49.
  73        Some applications are designed to work  with  the  default
  74        background,  using  colors  only  for  text.  For example,
  75        there are several implementations of the <STRONG>ls</STRONG> program  which
  76        use  colors to denote different file types or permissions.
  77        These "color ls" programs do not  necessarily  modify  the
  78        background  color, typically using only the <EM>setaf</EM> terminfo
  79        capability  to  set  the  foreground  color.   Full-screen
  80        applications  that  use default colors can achieve similar
  81        visual effects.
  82
  83        The first function, <EM>use</EM><STRONG>_</STRONG><EM>default</EM><STRONG>_</STRONG><EM>colors()</EM> tells the  curses
  84        library  to  assign terminal default foreground/background
  85        colors to color number  -1.  So  init_pair(x,COLOR_RED,-1)
  86        will  initialize  pair  x as red on default background and
  87        init_pair(x,-1,COLOR_BLUE)  will  initialize  pair  x   as
  88        default foreground on blue.
  89
  90        The  other,  <EM>assume</EM><STRONG>_</STRONG><EM>default</EM><STRONG>_</STRONG><EM>colors()</EM> is a refinement which
  91        tells which colors to paint for color pair 0.  This  func-
  92        tion  recognizes  a special color number -1, which denotes
  93        the default terminal color.
  94
  95        The following are equivalent:
  96               <EM>use</EM><STRONG>_</STRONG><EM>default</EM><STRONG>_</STRONG><EM>colors();</EM>
  97               <EM>assume</EM><STRONG>_</STRONG><EM>default</EM><STRONG>_</STRONG><EM>colors(-1,-1);</EM>
  98
  99        These are ncurses extensions.  For other curses  implemen-
 100        tations,  color  number -1 does not mean anything, just as
 101        for ncurses before a successful call  of  <EM>use</EM><STRONG>_</STRONG><EM>default</EM><STRONG>_</STRONG><EM>col-</EM>
 102        <EM>ors()</EM> or <EM>assume</EM><STRONG>_</STRONG><EM>default</EM><STRONG>_</STRONG><EM>colors()</EM>.
 103
 104        Other  curses  implementations do not allow an application
 105        to modify color pair 0.  They assume that  the  background
 106        is COLOR_BLACK, but do not ensure that the color pair 0 is
 107        painted to match the assumption.  If your application does
 108        not use either <EM>use</EM><STRONG>_</STRONG><EM>default</EM><STRONG>_</STRONG><EM>colors()</EM> or <EM>assume</EM><STRONG>_</STRONG><EM>default</EM><STRONG>_</STRONG><EM>col-</EM>
 109        <EM>ors()</EM> ncurses will paint a white  foreground  (text)  with
 110        black background for color pair 0.
 111
 112
 113 </PRE>
 114 <H2><a name="h2-RETURN-VALUE">RETURN VALUE</a></H2><PRE>
 115        These functions return the integer <STRONG>ERR</STRONG> upon failure and <STRONG>OK</STRONG>
 116        on success.  They will fail if either  the  terminal  does
 117        not  support  the <EM>orig</EM><STRONG>_</STRONG><EM>pair</EM> or <EM>orig</EM><STRONG>_</STRONG><EM>colors</EM> capability.  If
 118        the <EM>initialize</EM><STRONG>_</STRONG><EM>pair</EM> capability is not found,  this  causes
 119        an error as well.
 120
 121
 122 </PRE>
 123 <H2><a name="h2-NOTES">NOTES</a></H2><PRE>
 124        Associated  with  this  extension,  the <STRONG>init_pair</STRONG> function
 125        accepts negative arguments to specify  default  foreground
 126        or background colors.
 127
 128        The  <EM>use</EM><STRONG>_</STRONG><EM>default</EM><STRONG>_</STRONG><EM>colors()</EM>  function  was  added to support
 129        <EM>ded</EM>.  This is a full-screen application which uses  curses
 130        to  manage only part of the screen.  The bottom portion of
 131        the screen, which is of adjustable size, is left uncolored
 132        to  display the results from shell commands.  The top por-
 133        tion of the screen colors filenames using  a  scheme  like
 134        the  "color  ls" programs.  Attempting to manage the back-
 135        ground color of the screen for this application would give
 136        unsatisfactory  results  for  a  variety of reasons.  This
 137        extension was devised after noting that color  xterm  (and
 138        similar  programs)  provides a background color which does
 139        not necessarily correspond to  any  of  the  ANSI  colors.
 140        While  a special terminfo entry could be constructed using
 141        nine colors, there was no mechanism provided within curses
 142        to  account for the related <EM>orig</EM><STRONG>_</STRONG><EM>pair</EM> and <EM>back</EM><STRONG>_</STRONG><EM>color</EM><STRONG>_</STRONG><EM>erase</EM>
 143        capabilities.
 144
 145        The <EM>assume</EM><STRONG>_</STRONG><EM>default</EM><STRONG>_</STRONG><EM>colors()</EM> function was added to solve  a
 146        different  problem:  support  for applications which would
 147        use  environment  variables  and  other  configuration  to
 148        bypass  curses'  notion  of the terminal's default colors,
 149        setting specific values.
 150
 151
 152 </PRE>
 153 <H2><a name="h2-PORTABILITY">PORTABILITY</a></H2><PRE>
 154        These routines are specific to  ncurses.   They  were  not
 155        supported  on  Version 7, BSD or System V implementations.
 156        It is recommended that any code depending on them be  con-
 157        ditioned using NCURSES_VERSION.
 158
 159
 160 </PRE>
 161 <H2><a name="h2-SEE-ALSO">SEE ALSO</a></H2><PRE>
 162        <STRONG><A HREF="curs_color.3x.html">curs_color(3x)</A></STRONG>, <STRONG>ded(1)</STRONG>.
 163
 164
 165 </PRE>
 166 <H2><a name="h2-AUTHOR">AUTHOR</a></H2><PRE>
 167        Thomas  Dickey  (from  an analysis of the requirements for
 168        color xterm for XFree86 3.1.2C, February 1996).
 169
 170
 171
 172                                                      <STRONG><A HREF="default_colors.3x.html">default_colors(3x)</A></STRONG>
 173 </PRE>
 174 <div class="nav">
 175 <ul>
 176 <li><a href="#h2-NAME">NAME</a></li>
 177 <li><a href="#h2-SYNOPSIS">SYNOPSIS</a></li>
 178 <li><a href="#h2-DESCRIPTION">DESCRIPTION</a></li>
 179 <li><a href="#h2-RETURN-VALUE">RETURN VALUE</a></li>
 180 <li><a href="#h2-NOTES">NOTES</a></li>
 181 <li><a href="#h2-PORTABILITY">PORTABILITY</a></li>
 182 <li><a href="#h2-SEE-ALSO">SEE ALSO</a></li>
 183 <li><a href="#h2-AUTHOR">AUTHOR</a></li>
 184 </ul>
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